Editing Beam-powered propulsion (section)

==Electric propulsion==
Some proposed spacecraft propulsion mechanisms use [[electrically powered spacecraft propulsion]], in which electrical energy is used by an electrically powered rocket engine, such as an [[ion thruster]] or [[plasma propulsion engine]]. Usually, these schemes assume either solar panels or an onboard reactor. However, both power sources are heavy.

Beamed propulsion in the form of a laser can send power to a [[photovoltaic panel]] for ''Laser electric propulsion.'' In this system, if a high intensity is incident on the solar array, careful design of the panels is necessary to avoid a fall-off in conversion efficiency due to heating effects. John Brophy has analyzed the transmission of laser power to a photovoltaic array powering a high-efficiency electric propulsion system as a means of accomplishing high [[delta-V]] missions such as an [[Interstellar travel|interstellar]] precursor mission in a [[NASA Innovative Advanced Concepts]] project.<ref>John Brophy, ''[https://www.nasa.gov/directorates/spacetech/niac/2018_Phase_I_Phase_II/Breakthrough_Propulsion_Architecture_for_Interstellar_Precursor_Missions/ A Breakthrough Propulsion Architecture for Interstellar Precursor Missions]'', NASA, March 30, 2018. Accessed Nov. 18, 2019.</ref>

A microwave beam could be used to send power to a [[rectenna]] for ''microwave electric propulsion''. [[Microwave]] broadcast power has been practically demonstrated several times (e.g., in Goldstone, California, in 1974). Rectennas are potentially lightweight and can handle high power at high conversion efficiency. However, rectennas must be huge for a significant amount of power to be captured.